Dissertations / Theses on the topic 'A service life'

Godkänd; 2013; 20130529 (kimber); Tillkännagivande disputation 2013-09-11 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Kim Berglund Ämne: Maskinelement/Machine Elements Avhandling: Predicting Wet Clutch Service Life Performance Opponent: Professor Homer Rahnejat, School of Mechanical and Manufacturing Engineering, Loughborough University, Leicestershire, UK Ordförande: Bitr professor Pär Marklund, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Fredag den 4 oktober 2013, kl 09.00 Plats: D770, Luleå tekniska universitet

Utility Computing is one of the most discussed business models in the context of Cloud Computing. Service providers are more and more pushed into the role of utilities by their customer's expectations. Subsequently, the demand for predictable service availability and pay-per-use pricing models increases. Furthermore, for providers, a new opportunity to optimise resource usage offers arises, resulting from new virtualisation techniques. In this context, the control of service quality and profit depends on a deep understanding of the representation of the relationship between business and technique. This research analyses the relationship between the business model of Utility Computing and Service-oriented Computing architectures hosted in Cloud environments. The relations are clarified in detail for the entire service life cycle and throughout all architectural layers. Based on the elaborated relations, an approach to a delivery framework is evolved, in order to enable the optimisation of the relation attributes, while the service implementation passes through business planning, development, and operations. Related work from academic literature does not cover the collected requirements on service offers in this context. This finding is revealed by a critical review of approaches in the fields of Cloud Computing, Grid Computing, and Application Clusters. The related work is analysed regarding appropriate provision architectures and quality assurance approaches. The main concepts of the delivery framework are evaluated based on a simulation model. To demonstrate the ability of the framework to model complex pay-per-use service cascades in Cloud environments, several experiments have been conducted. First outcomes proof that the contributions of this research undoubtedly enable the optimisation of service quality and profit in Cloud-based Service-oriented Computing architectures.

Untreated wooden cladding has a long tradition and has in recent years become a both economically and environmentally beneficial solution in miscellaneous modern building applications. Untreated wood in cladding and similar applications represents a building part that changes its appearance rather dramatically without compromising its technical functionality. The aesthetic service life is often the decisive criterion for these applications. This thesis comprises a study on the weathering of untreated, i.e. unpainted wood. Following the service life prediction methodology suggested in the ISO 15686 standard, wood was weathered both outdoors and in two laboratory weathering apparatuses. Climate data for the test site were assessed including temperature, wind-driven rain and solar radiation. The performance of non-structural wood components in exterior above-ground applications is often closely related to the aesthetics of the wooden component in question. Hence, a method for color determination of large samples was developed, and the topic of human color perception is discussed briefly. It was found that the colonization by mold growth fungi contributes significantly to its surface appearance. Differences between materials and exposure directions were investigated. The topic of limit-state for aesthetic service life is discussed and a possible assessment method for such applications is presented. No simple dose-response relationship between solar radiation and wind-driven rain, and color response of the material could be established. Acceleration factors for the conducted laboratory weathering tests are discussed. Furthermore, color changes by outdoor versus laboratory weathering were evaluated. It was found that the conducted laboratory weathering cycles could not recreate the visual appearance of an outdoor weathered surface. In summary, the suggested bottom-up approach of the service life prediction methodology is not easily adaptive for wood in this application

Dissertation (Ph.D.)--University of Toledo, 2005.
Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Engineering." Bibliography: leaves 69-74.

Pre-mature deterioration of reinforced concrete causesproblems world-wide and the search for reliable cost effectiveand environmental friendly repairs is intense. The service lifeof the repaired structure is important in order to establishthe annual cost and environmental impact for differentalternatives. This doctoral thesis focuses on the service lifeof concrete bridge decks repaired with bonded concreteoverlays. The approach was broad and based on the performanceof a number of bridge decks after approximately ten years inservice. The main aims were to establish the overall servicelife and to improve the design where improvements were needed.Efforts have been made to make the repairs as robust aspossible and the crucial production stage is always considered.The following parameters were investigated:

    Wear and rutting

    Bond strength and extent and cause of cracks

    Relative humidity and temperature in the deck

    Freeze-thaw resistance and number of freeze-thawcycles

    Concrete cover and service life criterion with respect tochloride initiated corrosion

    Service life predictions using moving boundarytheory

    Chloride concentrations in de-icing water and in thesurfaces of concrete overlays

    Absorption of water and chloride ions due to capillarysuction of de-icing water

    Chloride ingress in solid and cracked parts of bondedconcrete overlays

The wear and rutting were found to be limited. The bondbetween new and old concrete was unaltered or increased afterten years in service. The cracking on the overlays wasgenerally limited. The main cracking causes were insufficientcuring and reflective cracking due to construction joints (coldcasting joints) in the old bridge deck. The cracks can beavoided or made non-hazardous with respect to corrosion andfreeze-thaw damages with simple measures.

The chloride ingress was low in solid and limited in crackedparts of the overlay. Samples of concrete, snow, slush andwater were taken from the overlay during two years to quantifythe chloride concentrations and their variations. The chlorideconcentration interacted with the weather, the local climateand the salt-spreading procedures. The chloride content in theoverlays was affected to at least 10 mm from the surface.

The relative humidity in the overlay was stable and low atapproximately 20 mm from the wear surface. The number of(salt)-freeze-thaw cycles was high. The thickness of theoverlays was found to be fairly normal distributed and this wasused in the service life predictions.

The moving boundary method is suitable to predict theingress of a chloride threshold value. The method is easy touse with a probabilistic approach and simple and cheap toupdate and no parameters have to be guessed. Numerical methodswere also used and the influence of various surfaceconcentrations was investigated. The transport of chloride ionsinto cracked concrete was treated with a two dimensional modeland the influence of crack depth was found to be limited.

Both conventional capillary absorption tests and cyclicwetting and drying test out-doors were conducted on matureconcrete cast and aged in-situ. The conclusion was thatcapillary suction of de-icing water could be the dominatingfactor in the chloride absorption process.

Key words: Repairs, bridge decks, bonded concreteoverlays, service life, chloride ingress.

A model to determine the time to the End of Functional Service Life (EFSL) for concrete bridge decks in Virginia was developed. The service life of Virginia bridge decks is controlled by chloride-induced corrosion of the reinforcing steel. Monte Carlo resampling techniques were used to integrate the statistical nature of the input variables into the model. This is an improvement on previous deterministic models in that the effect of highly variable input parameters is reflected in the service life estimations. The model predicts the time required for corrosion to initiate on 2% of the reinforcing steel in a bridge deck and then a corrosion propagation time period, determined from empirical data, is added to estimate the EFSL for a given bridge deck or set of bridge decks. Data from 36 Virginia bridge decks was collected in order to validate the service life model as well as to investigate the effect of bridge deck construction specification changes. The bridge decks were separated into three distinct groups: 10 bare steel reinforcement decks â 0.47 water/cement (w/c), 16 Epoxy-Coated Reinforcement (ECR) decks â 0.45 w/c, and 10 ECR decks â 0.45 w/(c+pozzolan). Using chloride titration data and cover depth measurements from the sampled bridge decks and chloride corrosion initiation values determined from the literature for bare steel, service life estimates were made for the three sets of bridge decks. The influence of the epoxy coating on corrosion initiation was disregarded in order to allow direct comparisons between the three sets as well as to provide conservative service life estimates. The model was validated by comparing measured deterioration values for the bare steel decks to the estimated values from the model. A comparison was then made between the three bridge deck sets and it was determined that bridge decks constructed with a 0.45 w/(c+p) will provide the longest service life followed by the 0.47 w/c decks and the 0.45 w/c decks, respectively. From this it can be inferred that the addition of pozzolan to the concrete mix will improve the long-term durability of a bridge deck while a reduction in w/c appears to be of no benefit.
Ph. D.

Pipelines are extensively used engineering structures for conveying of fluid from one place to another. Most of the time, pipelines are placed underground, surcharged by soil weight and traffic loads. Corrosion of pipe material is the most common form of pipeline deterioration and should be considered in both the strength and serviceability analysis of pipes. The study in this research focuses on two different types of buried pipes including concrete pipes in sewage systems (concrete sewers) and cast iron water pipes used in water distribution systems. This research firstly investigates how to involve the effect of corrosion as a time dependent process of deterioration in the structural and failure analysis of these two types of pipes. Then two probabilistic time dependent reliability analysis methods including first passage probability theory and the gamma distributed degradation model are developed and applied for service life prediction of the pipes. The obtained results are verified by using Monte Carlo simulation technique. Sensitivity analysis is also performed to identify the most important parameters that affect pipe failure. For each type of the pipelines both individual failure mode and multi failure mode assessment are considered. The factors that affect and control the process of deterioration and their effects on the remaining service life are studied in a quantitative manner. The reliability analysis methods which have been developed in this research, contribute as rational tools for decision makers with regard to strengthening and rehabilitation of existing pipelines. The results can be used to obtain a cost-effective strategy for the management of the pipeline system. The output of this research is a methodology that will help infrastructure managers and design professionals to predict service life of pipeline systems and to optimize materials selection and design parameters for designing pipelines with longer service life.

This research utilizes the Model for Marketing in Small Professional Service Firms, based on Carson's Model for the Development of Small Firm Marketing, to examine the marketing of Physician Services in Puerto Rico. To achieve its objectives, a combination of quantitative(survey) and qualitative (cases) research is used. From the literature a series of statements is generated to form hypotheses that are tested utilizing the results of a questionnaire survey of 105 physicians in Puerto Rico. The results suggest a possible change of attitude of service providers towards marketing and its use. They reveal that physicians in Puerto Rico are in agreement with the marketing concept but most do not adopt "traditional" techniques of marketing- preferring to focus on the physician/patient relationship. Analysis of eight cases demonstrates the importance of this relationship and suggests that though is seen as important in attracting and retaining patients, most physicians do not see this as marketing, which is perceived to be mostly "advertising" and "selling." Many are cautious not to "commercialise" their practice and any differences in their behaviour can be explained by the way they believe the physician/patient relationship is best enhanced. The research proposes a Model for Marketing Solo Professional Service Firms that depicts the_ relation between the changes, over time, in the personal life cycle of the service provider/owner manager and the stages in the life cycle of the business practice. The model suggests that throughout there is a need to focus on one aspect of marketing for the practice, which may change over time, and that the elements determining the marketing activities at a particular time, how they are undertaken and why they are utilised, are constantly evolving. Thus the marketing practices of small professional firms appear to be contingent on both the external and internal environment of the practice.

AN ABSTRACT OF THE THESIS OF RODNEY H. WELDON, for the Masters of Science degree in WORKFORCE EDUCATION, presented on APRIL 28, 2012, at Southern Illinois University Carbondale. TITLE: AGING AUTOMOTIVE TECHNICIANS EXTEND THEIR WORK LIFE THROUGH SERVICE TEAMS SEEKING TOTAL SERVICE EXCELLENCE MAJOR PROFESSOR: Dr. Elizabeth Freeburg The purpose of this paper was to contribute to the body of knowledge about the automotive technician's work life. More specifically, the study addressed the identification of change in technician production, how this change affects and was affected by the issues through out their work life. The author analyzed automotive technician productivity and efficiency calculations of automotive dealership technician production and the issues that impacted change. 40 years of hands on service department management recalled from the researchers personal records applied what worked and redefined what did not.

This study examined the effect of service activities on the development of leadership life skills in youth and if having a reflection component as part of the activity makes a difference. Additionally, the study examined the impact of selected demographics including age, gender, type of service completed monthly and 4-H membership on the development of leadership life skills. Participants in the study were from two samples. One group represented the El Paso National Youth Service Day, the other represented the District 11 4-H Leadership Lab in Brenham, Texas. Participants were randomly assigned to a control (no reflection) or treatment (with reflection) group. Youth participants self rated their leadership life skills using a 33-question post-test only questionnaire. Demographics were reported in nine additional questions. The major findings of the study are as follows: 1) Overall, the participants reported their perceived leadership life skills to be high in four of the five subscales; 2) The inclusion of a reflection component did not significantly affect perceived leadership life skills; 3) Type of service, whether direct or indirect, had a significant impact on perceived leadership life skills; 4) 4-H membership had a significant impact on the Personal Leadership Development subscale.

Current software community players like academy and industry have been changing the traditional paradigms of software engineering towards context-awareness and distributed computing. Nowadays, service-oriented computing and context-aware computing are two emerging paradigms that are changing the way of designing, developing, providing and consuming software services. Whilst service-oriented computing is based on service-oriented architectures and it is focused on modelling functionality and providing flexible software services, context-aware computing is based on the context life cycle and it allows processing and changing the behaviour of such services given certain context information. The synergy between both paradigms is a core research topic in ubiquitous and pervasive computing widely applied to the Internet of Things and Smart Cities.In the present PhD thesis, we exploit this synergy by focusing on context-aware computing from the perspective of service-oriented computing, which is also known as context-aware service-oriented computing. Such research topic involves the management of context within different essential phases of the context life cycle that show how the context data moves from phase to phase in software services within the paradigm of the service-oriented computing. Hence, the work done in this thesis involves different components and processes that have the aim to accomplish the context life cycle, namely the acquisition, modelling, reasoning and dissemination of the context in service-oriented computing. Particularly, we make an effort to provide both a context ontology for context modelling, context reasoning and high-level context dissemination, and a context-aware monitoring architecture for context acquisition and low-level context dissemination.Such work of the thesis has been motivated for contributing in the solution of different issues mainly identified in the phases of context modelling and context acquisition that are a strong basis of the context life cycle. Firstly, in the context modelling we mainly identified the proliferation of several context models presenting some problems about: reusability, extensibility and adaptation. Secondly, in the context acquisition we mainly identified that existing monitoring infrastructures are not prepared to support the constant changes in their context and the context of other entities, including the services that they are supervising which provoke the provisioning of context data that is not reliable. In summary, this thesis explores three big research questions: 1) What context data to acquire and to model? This involves the study of the current state of the art of context models, specifically: which are these proposals and how are they related, what are their structural characteristics, what context information is the most addressed, and what are their most consolidated definitions. 2) How to model context data? This involves the development of a three-level context ontology with the aim of improving the reusability, extensibility and adaptation capabilities of existing context models. 3) How to acquire context data? This involves the development of a context-aware monitoring architecture that can be easily configured, adapted or evolved according to the constant changes of the context.The context model and the architecture proposed in this PhD thesis are validated through different scenarios and use cases, highlighting their integration in SUPERSEDE (www.supersede.eu), a European project in the H2020 program for fulfilling some requirements of data acquisition and management demonstrating that the context life cycle is supported.
Els actors actuals de la comunitat de software, com l'acadèmia o la indústria, han anat canviant els paradigmes tradicionals de l'enginyeria de software cap a la sensibilitat al context i la computació distribuïda. Avui dia, la computació orientada a serveis i la computació conscient del context són dos paradigmes emergents que estan canviant la forma de dissenyar, desenvolupar, proporcionar i consumir serveis de software. Mentre que la computació orientada a serveis es basa en arquitectures orientades a serveis i se centra en el modelatge de la funcionalitat i la prestació de serveis de software flexibles, la computació sensible al context es basa en el cicle de vida del context i permet el processament i canviar el comportament d'aquest tipus de serveis donada una determinada informació del context. La sinergia entre els dos paradigmes és un tema central de recerca a la computació ubiqua i omnipresent, àmpliament aplicada a la Internet de les coses i les ciutats intel·ligents. En la present tesi doctoral explotem aquesta sinèrgia, centrant-se en la computació sensible al context des de la perspectiva de la computació orientada a serveis, que també es coneix com computació orientada a serveis sensibles al context. Tal tema de recerca implica la gestió de contexts en diferents fases essencials del cicle de vida del context que mostren com les dades de context es mouen d'una fase a l’altra en serveis de software dins del paradigma de la computació orientada a serveis. Per tant, el treball realitzat en aquesta tesi consisteix en diferents components i processos que tenen l'objectiu d'aconseguir el cicle de vida del context, és a dir, l'adquisició, el modelatge, el raonament i la difusió del context en computació orientada a serveis. En particular, fem un esforç per proporcionar tant una ontologia de context per a la modelització, raonament i difusió del context d'alt nivell, i una arquitectura de monitorització sensible al context per a l'adquisició i difusió del context de baix nivell. Aquest treball de tesi ha estat motivat per contribuir a la solució dels diferents problemes identificats principalment en les fases de modelatge de context i adquisició de context que són una base sòlida del cicle de vida del context. En primer lloc, en el modelatge de context es van identificar principalment la proliferació de diversos models de context que presenten alguns problemes sobre: reutilització, l'extensibilitat i l'adaptació. En segon lloc, en l'adquisició del context identifiquem principalment que les infraestructures de monitorització existents no estan preparats per suportar els canvis constants en el seu context i el context d'altres entitats, incloent-hi els serveis que s'estan supervisant, que provoquen un aprovisionament de dades de context que no és fiable. En resum, aquesta tesi explora tres grans preguntes de recerca: 1) Quines dades de context cal adquirir i modelar? Això implica l'estudi de l'estat actual de la tècnica dels models de context, en concret: ¿quines són aquestes propostes i com es relacionen, quines són les seves característiques estructurals, quina informació de context és la més adreçada, i quines són les seves definicions més consolidades. 2) Com modelar les dades de context? Això implica el desenvolupament d'una ontologia de context de tres nivells amb l'objectiu de millorar les capacitats de reutilització, extensibilitat i adaptació dels models de context existents. 3) Com adquirir dades de context? Això implica el desenvolupament d'una arquitectura de monitorització sensible al context que pot ser fàcilment configurat o adaptat d'acord amb els canvis del context. El model de context i l'arquitectura proposada en aquesta tesi doctoral es validen a través de diferents escenaris i casos d'ús, destacant la seva integració en SUPERSEDE, un projecte europeu en el programa H2020 per al compliment d'alguns requisits d'adquisició i gestió de dades que demostra que es dóna suport al cicle de vida del context.

Vacuum insulation panels, VIPs, constitute a new insulation material, 6 to 8 times better than traditional insulation materials, which utilizes the positive influence vacuum has on the thermal properties of certain materials. A VIP is a composite with a flat core enclosed by an envelope preventing the core to fill with gas. The vacuum in the core is vital to reach thermal conductivities down to 0,0035 W/(m K), if the vacuum is lost the panel has reached the end of its service life time. Metal sheets would the preferred material to create an impermeable envelope but would creates a large thermal bridge at the edges of a panel when it folds over the edges of the panel.

A serpentine edge has been proposed in order to deal with this large thermal bridge. This serpentine edge has been evaluated first as a numeric model in software and then by measuring on a prototype edge element in a hot and cold plate instrument. Measured temperatures were used to validate the numerical model. Results show that a serpentine edge can greatly reduce the thermal bridge if designed correctly.

Another direction taken in the development of the VIP barrier is to use very thin metal layers, metallization layer or coating, incorporated into multi layered polymer composite film. This creates barrier films with very good barrier properties and only small thermal bridges. The modeling of gas flux through films with more than one coating has only just started. Existing models for flux through multi coated films all assume that flux is only taking place through defects in the coating layers, that all defects are of the same size and that all defects are positioned in square lattices. The model discussed herein use the same assumption of flux through pinholes only but it does take defect sizes and positions into account. Barrier film, from a regular vacuum insulation panel, with double coatings has been evaluated in light microscopy to characterize the defects in each of the coatings. The data found have been fed into the model and the results comply well with reported permeabilities of similar barrier films.

Increasing the severity of the stress history of a structure reduces it's service life. Feasibility studies to increase the zero fuel weight of the P-3 Orion depend heavily on the resulting decrease in service life of the wing box and airframe. One option of extending the service life of existing aircraft is through the replacement or augmentation of critical structural members with composite materials. Since structural composites do not yet have adequate service life statistics, life predication must be through probability modeling. Such modeling can begin with experimental data on accelerated testing of fiber life under several sustained load levels. This data can be the basis for an appropriate strength-life model of the fiber which can in term be related to the strength-life model of the composite by the local-load sharing model. The local load sharing model captures the physical failure sequence of fiber failure within a composite. Such a strength-life model, when combined with structural analysis, can be used to predict an airframe's service life under the changed conditions associated with the zero fuel weight increase

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
O presente trabalho tem o propósito de apresentar a Campanha da Fraternidade como uma das grandes expressões da Igreja do Brasil a serviço da vida. Para atingir seu objetivo, o trabalho utiliza o método VER-JULGAR-AGIR e, inicialmente, relaciona a referida Campanha com os diferentes desafios impostos à Igreja que justificaram a sua origem, tanto em âmbito local, no Rio Grande do Norte, como em âmbito nacional, levando em consideração tanto a conjuntura nacional como eclesial. Depois, a reflexão mostra o desenvolvimento da Campanha e os fatores que influenciaram sua estrutura e sua metodologia. Como iluminativo teológico, é apresentada uma abordagem eclesiológica, tendo como referência central o Concílio Vaticano II e suas decorrências, com especial enfoque nos modelos de Igreja apresentados por Avery Dulles e contextualizados no Brasil pelo Pe. José Marins, e na Teologia desenvolvida na América Latina, sempre considerando os elementos conjunturais eclesiais e sócio-econômicos que tiveram influência na eclesiologia. A Conferência Nacional dos Bispos do Brasil realiza a Campanha da Fraternidade todos os anos procurando responder aos problemas que estão presentes na realidade brasileira e causam sofrimento, dor e morte. As Campanhas da Fraternidade realizadas no novo milênio mostram que a Igreja do Brasil é uma Igreja serva, que procura resgatar o valor e a dignidade da pessoa humana. Assim, a Igreja do Brasil está a serviço da Vida através da Campanha da Fraternidade.
The purpose of the current study is to present the Fraternity Campaign as one of the big expressions of the Brazilian Church in the service of life. In order to achieve its objective, the study uses the SEE-THINK-ACT method and initially relates the Campaign mentioned to the different challenges imposed to the Church which have justified its creation, either within a local scope, in Rio Grande do Norte, or within a national scope, taking into consideration the national as well as the ecclesiastical junctures. Later the reflection shows the development of the Campaign and the factors which influenced its structure and its methodology. An ecclesiological approach is presented as a theological illuminative, having as main reference the Second Vatican Council and its consequences, with special focus on the Church models presented by Avery Dulles and put into context in Brazil by Fr. José Martins, and on the Theology developed in Latin America, always considering the ecclesiastical and socio-economic juncture elements which have influenced ecclesiology. The National Conference of Brazilian Bishops conducts the Fraternity Campaign every year seeking answers to current problems in Brazilian reality, those which cause grief, pain and death. The Fraternity Campaigns carried out in the new millennium show that the Brazilian Church is a serving Church, that tries to rescue the value and dignity of human beings. Therefore, the Brazilian Church is in the service of life through the Fraternity Campaign.

Thesis: S.M. in Mechanical Engineering, and S.M in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 71-74).
New regulations in the United States and Europe, designed to address climate change concerns by reducing greenhouse gas emissions, are causing increased use of gasoline direct-injection (GDI) engines in light-duty vehicles (LDV). Separate new regulations that aim to reduce particulate emissions to address air pollution concerns are taking effect concurrent with greenhouse gas limitations in both jurisdictions. GDI engines are proven to create more particulate emissions than previously utilized port-injection technology. Increasing particulate emissions rates combined with falling regulatory particulate emissions limits requires new strategies to reduce these emissions from gasoline powered LDVs. Particulate filters have been successfully implemented to reduce particulate emissions from diesel engine exhaust for over a decade. Diesel particulate filters have a demonstrated filtration efficiency of 95% or greater and have reduced diesel particulate mass (PM) emissions by one to two orders of magnitude. GDI engines require no more than one order of magnitude reduction in particulate emissions to meet new regulations. Existing particulate filter technology in use in diesel vehicles is capable of reducing GDI engine emissions to new regulatory levels; however, it is proposed that these reduction may be achievable through means other than gasoline particulate filters (GPF). A GPF will create an additional back-pressure in the engine exhaust system that will reduce engine power and efficiency. This backpressure will increase as PM is trapped in the filter and decrease as combustible PM removed. A buildup of incombustible ash present in engine-out PM will increase the baseline backpressure of the filter during the course of its service life. It is important to understand the impact of ash on the filter pressure drop performance before implementing GPF to meet new emissions regulations. This study builds on existing diesel particulate filter technology and demonstrates through experimental results the mechanisms by which ash increases GPF pressure drop. Ash deposits are also shown to increase the light-off temperature of three-way catalyst coatings in GPF.
by Nicholas C. Custer.
S.M. in Mechanical Engineering, and S.M in Naval Architecture and Marine Engineering

This study was carried out to enhance the durability of concrete exposed to chloride attack by means of two approaches: (i) to design sustainable concrete compositions and (ii) to apply suitable maintenance techniques consisting of electrochemical chloride extraction (ECE) and surface coating (SC) treatments. Subsequently, the study was divided into two separate phases for this study. The first phase was to assess the role of the cement combinations on enhancing chloride resistance of concrete. The cement combinations composed of, Portland cement (PC)/fly ash (FA) and PC/ground granulated blast furnace slag (GGBS) in binary mixes, and with silica fume (SF), metakaolin (MK) and limestone (LS) as addition to form ternary concretes. The w/c ratio of concrete was selected in the range of 0.35 to 0.45 for the requirement of high performance. To improve the degree of accuracy, four contemporary chloride test methods were used in this work to measure the chloride penetration of concrete, which are: (i) Method A-rapid chloride permeability test to ASTM C1202; (ii) Method B-chloride migration test to NT Build 492; (iii) Method C-Multi-Regime test to UNE 83987:2009; and (iv) Method D-chloride diffusion test to CEN/TS 12390-11. The variability of different methods was evaluated and the correlation between them discussed. In addition, the microstructure and chloride binding capacity of relevant cement paste were investigated in order to provide more information for assessing the improvement on chloride resistance of different binary/ternary mixes. The results indicated that the chloride resistance of concrete was benefited significantly when blended with additional cement combinations. The concrete blended with FA or FA/LS showed no contribution on improving chloride resistance before the age of 28 days, but significant improvement up to age of 90 days. Compared to 100PC concrete at the equal w/c ratio, generally, it demonstrated 3-7 times decrease of the chloride durability indicators in the binary and ternary concrete. When comparison was conducted at equal strength grades (45, 55, and 65 N/mm2), the improvement on the chloride durability was more significant in the binary and ternary concrete. However, for individual binary or ternary concrete, the decrease in w/c ratio from 0.45 to 0.35 did not cause significant expected reduction in the chloride diffusion coefficient, especially when w/c ratio went down below 0.4. This was mainly attributed to the reduction of chloride binding capacity (loss of accessible binding sites to chlorides) of concrete caused by decreasing w/c ratio, although which still can refine the pore structure of concrete. The maintenance approach is necessary and inevitable when the chloride durability of designed concrete is insufficient to satisfy the designed working life. The second phase investigated the application of suitable maintenance approach involving ECE and SC treatment on the chloride contaminated concrete prior to the corrosion of embedded steel. The selected specimens were 100PC, 70PC30FA and 50PC50GGBS concrete with w/c ratio of 0.35, 0.45 and 0.55. Chloride was driven into 28-day concrete under the migration test rather than mixing at time of casting concrete. Two cycles of ECE process were applied on concrete, and then the pore structure characteristics and carbonation resistance of concrete were measured. Those specimens, including reference concrete, desalinated concrete and desalinated concrete coated with coating materials (Silane and RheoFIT®790) were placed into the artificial spraying salt solution of 1.0 mole/litre concentration for 30 days. The chloride content profile of sprayed specimens were obtained, and used to calculate the chloride diffusion coefficient based on three different calculation methods. The observations stated that approximately 65% of penetrated chloride was extracted during two cycles of ECE treatment for 100PC and 70PC30FA concrete, and about 57% for the 50PC50GGBS concrete. The ECE treatment increased the porosity of all mixes due to movement of ions and dissolution of solid phase in concrete, while much more significant in 50PC50GGBS concrete than 100PC and 70PC30FA concrete. It also reduced significantly the carbonation resistance of concrete at early exposure time (before 6 weeks), but insignificantly up to 10 weeks exposure period. Additionally, it showed significant increase of chloride diffusion coefficient in the desalinated 50PC50GGBS concrete compared to the non-desalinated concrete. However, the influence of chloride diffusion coefficient was not significant in the desalinated 100PC and 70PC30FA concrete. Coating materials performed effectively on preventing chloride ingress from a spraying environment according to the comparison of chloride profile between coated and uncoated specimens, except for the RheoFIT®790 coated on 100PC concrete. Based on the current calculation methods for the chloride profile, the calculated chloride diffusion coefficient of coated concrete also demonstrated significant reduction compared to those uncoated concrete. Finally, the predicted service life of concrete after ECE and SC treatment demonstrated long extended life for 70PC30FA concrete, where only ECE treatment can increase total service life by 47%-66%. Both ECE and SC (Silane with 50 years working life) treatments will extend total service life to maximum 1.9-2.5 times, and minimum 1.7-2.0 times. The extended service life is highly related to the working life of coating materials. However, for 50PC50GGBS concrete (with increasing chloride diffusion coefficient caused by ECE treatment), only 3%-4% increase of the total service life was found due to the ECE treatment. Both ECE and SC (Silane with 50 years working life) treatments can offer extension of service life to maximum of 1.3-2.2 times, and minimum of 1.2-1.3 times.

Over the last few decades, the increasing premature deterioration of reinforced concrete structures, mainly due to rebar corrosion, has become a worldwide concern. This has been attributed to insufficient quality and quantity of cover concrete resulting from inadequate mix design and poor onsite workmanship respectively. Engineers also often lack understanding of concrete durability and prescribe insufficient cover depths relative to the exposure conditions. Concrete degradation has many financial and social implications on a larger scale. Direct costs relate to the repair and rehabilitation of existing structures to maintain serviceability while indirect costs include loss in productivity and reduced economic growth. With increasing demand for infrastructure and subsequent expansion of the built environment, there is greater need for concrete to withstand and perform in corrosive environments. Hence, designing for durability has gained significant importance amongst engineers and other stakeholders in the construction industry. Furthermore, the appearance of cracks can be considered as an inevitable phenomenon in the design life of reinforced concrete structures, due to concrete being an inherently cracked material. The presence of cracks within the cover zone changes the dynamics of transport mechanisms and corrosion development. Cracks provide preferential ingress paths for deleterious species such as chlorides and this leads to a reduction in the time taken for reinforcement corrosion initiation and thus reduces the service life of the structure. Most service life models also consider concrete only in the uncracked state, leading to an overestimation of the actual performance and design life of reinforced concrete infrastructure. Extensive research has been carried out to find means to promote the service life of reinforced concrete structures in aggressive environments. Hydrophobic (silane) impregnation represents a cost-effective way to increase the durability of concrete structures in cases where insufficient cover quality and depth have been achieved. The hydrophobic impregnation agent lines the internal capillary pore structure and provides a water-repellent surface without affecting the external appearance of the concrete. Thus, the risk of reinforcement corrosion and subsequent deterioration can be reduced as the ingress of water-dissolved aggressive species is minimised or prevented. The influence of silane impregnation on chloride ingress is well documented in literature and several experiments have been carried out over the last decades. However, there is limited work on the service life modelling of silane treated concrete. Hence, the purpose of this study was to investigate and quantify the influence of silane impregnation as a remedial measure for poor quality cover or insufficient cover depth in newly constructed structures and ultimately predict the time to corrosion initiation for specific cover depths and concrete types. The effectiveness of silane impregnation in cracked concrete was also studied. Two w/b ratios (w/b = 0.45 and w/b = 0.60) and four binder types (CEM I 52.5N, Fly-ash (FA), Ground granulated Corex slag (GGCS) and CEM III/B 42.5N) were selected. Hence, a total of 8 main (normal) concrete mixes and 4 poor quality mixes were used. Poor quality concrete was produced by exposing the concrete specimens to relatively high temperature at early age. Cracked concrete was obtained by loading notched reinforced beams until the formation of cracks. Steel spacers were then placed in the notch and the beams were unloaded to create crack widths of 0.2 mm and 0.6 mm (below and above the commonly assumed crack width threshold of 0.4 mm). Silane treatment was performed at a specimen age of 28 days by applying Sikagard®-706 Thixo at a consumption rate of 400 g/m2 . Several experimental tests were performed on untreated and silane treated concrete. Compressive strength and Durability Index (DI) tests were carried out to characterise the concrete mixes. Accelerated carbonation and moisture profiling tests were undertaken to assess the influence of silane impregnation on concrete carbonation and relative humidity. Finally, uncracked and cracked (untreated and treated) concrete mixes were ponded in sodium chloride (NaCl) solution for 80 days, followed by chloride profiling. The data for the uncracked concrete was curve fitted using a solution to Fick’s second law of diffusion. The regression parameters obtained (surface chloride concentration (Cs) and apparent chloride diffusion coefficient (Da)) were then incorporated in a mathematical solution to Fick’s second law to obtain suitable expressions that describe the penetration of chlorides with time for silane treated and untreated concrete mixes. Hence by determining the time taken for chloride concentration at the rebar level to reach the critical threshold (assumed to be 0.4% by mass of binder), the time to corrosion initiation of untreated and silane treated concrete was predicted for particular cover depths. The results indicate that the silane penetration depth is highly dependent on the quality (porosity) and moisture content of the near surface zone as deeper penetration was recorded in the higher w/b ratio and poor-quality concrete mixes. Silane impregnation also reduced the capillary absorption and chloride conductivity for all the mixes. In terms of the bulk diffusion test, chloride ingress in the treated concrete mixes was suppressed and lower chloride surface concentration (Cs) and apparent chloride diffusion coefficient (Da) were recorded. The influence of silane impregnation on carbonation was negligible in the w/b = 0.45 concrete mixes while a slight decrease in carbonation depth was observed in the w/b = 0.60 concrete mixes. The relative humidity of treated concrete (near the surface) initially increased relative to the untreated concrete. However, the difference in relative humidity between silane-treated and untreated concrete is reduced with time. Higher chloride concentrations were measured in the cracked concrete at depths of 50-60 mm compared to the uncracked concrete. Greater chloride ingress was also recorded in the 0.6 mm crack width relative to the 0.2 mm crack width. For a particular crack width, chloride ingress in cracked concrete was influenced by the type of binder; a significant reduction in chloride content was recorded in the cracked slag (GGCS and CEM III/B) concrete mixes relative to the CEM I mix. The results also suggest that silane impregnation reduces chloride ingress in cracked concrete (up to a crack with of 0.6 mm) and consequently minimises the risk of premature reinforcement corrosion initiation, especially in slag concrete. The service life prediction results emphasized the importance of adequate cover depths in the extreme marine exposure class (XS3) and highlighted the superior performance of slag concrete relative to CEM I concrete. A lower rate of chloride ingress was predicted in the silane treated concrete and consequently to achieve the same time to corrosion initiation, smaller cover depths are required. Alternatively, the results also show that the initiation period of rebar corrosion in structures with insufficient cover depth and quality can be effectively extended using silane impregnation.

Cloud computing has become a prominent paradigm to offer on-demand services for softwares, infrastructures and platforms. Cloud services are contracted by a service level agreement (SLA) between a cloud service provider (CSP) and a cloud service user (CSU) which contains service definitions, quality of service (QoS) parameters, guarantees and obligations. Cloud service providers mostly offer SLAs in descriptive format which is not directly consumable by a machine or a system. The SLA written in natural language may impede the utility of rapid elasticity in a cloud service. Manual management of SLAs with growing usage of cloud services can be a challenging, erroneous and tedious task especially for the CSUs acquiring multiple cloud services. The necessity of automating the complete SLA life cycle (which includes SLA description in machine readable format, negotiation, monitoring and management) becomes imminent due to complex requirements for the precise measurement of QoS parameters. Current approaches toward automating the complete SLA life cycle, lack in standardization, completeness and applicability to cloud services. Automation of different phases of the SLA life cycle (e.g. negotiation, monitoring and management) is dependent on the availability of a machine readable SLA. In this work, a structural specification for the SLAs in cloud computing (S3LACC in short) is presented which is designed specifically for cloud services, covers complete SLA life cycle and conforms with the available standards. A time efficient SLA negotiation technique is accomplished (based on the S3LACC) for concurrently negotiating with multiple CSPs. After successful negotiation process, next leading task in the SLA life cycle is to monitor the cloud services for ensuring the quality of service according to the agreed SLA. A distributed monitoring approach for the cloud SLAs is presented, in this work, which is suitable for services being used at single or multiple locations. The proposed approach reduces the number of communications of SLA violations to a monitoring coordinator by eliminating the unnecessary communications. The presented work on the complete SLA life cycle automation is evaluated and validated with the help of use cases, experiments and simulations.

An increasing number of women are returning to school as nontraditional students to complete their bachelor’s degrees. These women may have specific needs related to life transitions and re-entry into postsecondary education that traditional students do not. The purpose of this study was to gain insight into the experiences of women who are nontraditional students, including their everyday supports and challenges. The guiding research question for this study was: Upon identifying the challenges for women at a branch campus, what changes can the university make to better serve the women? Study participants included 12 students currently enrolled in a bachelor’s program in social work. Participants also included four university social work faculty and five campus administrators from the study site. A participatory action research methodology was used to collect data from multiple stakeholders. Interviews with social work faculty and university center and branch campus administrators were conducted. Data were coded using open and axial coding. NVivo 11 was employed to help facilitate the coding of the data for the study in order to assure accuracy in identifying common themes. The two main themes to emerge from this study were Experiences and Challenges. Participants’ experiences included personal and academic. Personal challenges that the women described included abuse, childcare, and health. The two forms of abuse described were substance abuse and domestic abuse, and the health subthemes included personal and family issues. Women’s academic challenges included finances, academic writing, and class schedules. Study results may be used to raise stakeholders’ awareness of students’ needs, explore and change university processes, and develop workshops to assist nontraditional female students with career development and financial literacy.

Policies for people with learning disabilities, as in the case with other groups of service users, have increasingly emphasised the importance of their involvement in the planning of their own services, and at a more general level in the development of their local authority community care plan and commissioning strategies. This thesis seeks to begin to explore some of the difficulties that may arise in attempting to implement such a policy through a case study of practices in one inner London Borough. The study includes a number of important interrelated themes including: the complexities of communication, normalisation, the nature of choice, citizenship and free will, and asks does social policy reform provision or create unrealistic expectations and burdens for social service professionals and service users. It is essentially a study about communication and its impact on choice and social inclusion. Focusing on communication between professionals and service users, their carers and advocates, the field study investigates the Council's strategic planning procedures in order to explore the relationship between service development and the preferences expressed by users. The findings are presented within a legislative framework, with particular interest paid to the government's White Papers 'Modernising Social Services,' 'Valuing People,' and the Best Value initiative. The study combines an historical account of policy development, and investigates social policies that have attempted to bring about change, while also exposing the contradictions within and between them. Because of this there are many challenges attached to this enterprise, and as a consequence the study is inevitably on a small scale and the answers it produces are tentative. Nevertheless it provides an indication of the nature and scale of the difficulties which social services will have to overcome if they are to make a reality of government policy in this area by engaging effectively with the personal experiences and lives of adults with learning disabilities and their carers.

This research focused on the service use of HIV-positive mothers. My aim was to explore service use from the perspective of users and potential users of voluntary and statutory social services for people with HIV infection. This approach was prompted by the assumption I thought to underlie much of the much of the literature on HIV services, namely, that once a need had been identified and a relevant service provided, and adequately publicised, it would be used. I decided to adopt a case study approach focused on Edinburgh. The city, with its relatively high prevalence of HIV infection and density of social services, provided an excellent location for a contextualised exploration of service use. To deepen my knowledge of this context, and prepare for interviews with HIV-positive mothers, I first interviewed ten service providers including funders and representatives of statutory and voluntary, child-centred and adult-focused services. My concern to explore the social processes, attitudes and experiences underlying the use and non-use of services informed my choice of qualitative methods. The study is primarily based on in-depth, semi-structured interviews with 12 women, who had lived with HIV infection for between seven and 12 years. To reflect the unpredictability of living with a chronic condition interspersed with acute episodes, I decided to interview the respondents twice over the course of some months. Drawing on the high level of intermediate analysis completed between the two interviews, the second interviews were also used to explore recurrent themes raised in the first interviews further, and to map the chronology of each respondent's service use against other important life events. My findings attest to the importance of exploring chronic illness and service use in the context of wider social, familial and caring relationships, as well as socioeconomic circumstances. I focus on the relationship between service use and a continuing process of post-diagnosis identity reconstruction. My analysis of this process relates not only to the diagnosis itself, but explores several other sources of, or influences on, post-diagnosis identity construction, and the inter-relationships between them. These include motherhood, work, intimate relationships, infonnal support and participation in service decision-making. The theoretical and policy implications of these findings for the development of services are also addressed.

Thesis (M.S.)--Air Force Institute of Technology, 2003.
Title from title screen (viewed May 10, 2004). "March 2003." Vita. "AFIT/GAQ/ENS/03-02." "ADA413132"--URL. Includes bibliographical references (leaves 132-135). Also issued in paper format.

The internal combustion engine requires clean air in order to operate without problems the entire service life. The air filter acts as a barrier between the ambient air ridden with particulate matter, and the sensitive interior of the engine. Several factors affect the air filter performance, such as pressure drop, efficiency, and dust holding capacity. Many external factors affect the air filter too, such as driving style, engine type, if the car is equipped with hybrid propulsion et cetera. The scope for this thesis work aims to extend the knowledge of air filtration for the customer, in this case, Volvo Cars. A comprehensive literature study along with benchmarking of competitors acts as a foundational approach. Regarding air filter service life, three parameters are identified as the most significant: dust holding capacity, efficiency and pressure drop over the filter element. Reverse engineering shows some competitor design decisions. A model of estimating air consumption is developed using a data-driven approach with real-world driving data as a basis. The model shows how much the actual air consumption varies between different markets and various engines. As a result, the service lifetime of air filters in certain cars with certain engines may be extended or allow for a smaller filter size for the same service lifetime.

Infrastructure management must move from a perspective that may singularly emphasize facility condition assessment to a broader view that involves nonphysical factors, which may substantially impact facility performance and shorten its service life. Socioeconomic, technological, regulatory, and user value changes can substantially increase the service expectations of existing facilities. Based on a theoretical framework drawn from prior work, this research develops a new approach to model infrastructure performance and assess factors that influence the remaining service life of highway bridges. Key parameters that impact the serviceability of highway bridges are identified and incorporated into a system dynamics model. This platform supports parametric scenario analysis and is applied in several cases to test how various factors influence bridge service life and performance. This decision support system provides a new approach for modeling serviceability over time and gives decision-makers an indication of: (a) the gap between society's service expectations and the service level provided and (b) the remaining service life of a highway bridge.
Ph. D.

Nowadays, circular economy is becoming more relevant in society. In the context of the automotive industry, we no longer simply work on emissions emitted during the vehicle use phase but rather on the environmental impacts induced during all phases of the vehicle's life cycle (manufacturing, logistics, use, maintenance and end of life). For this purpose, many automakers, including the Group PSA, use life cycle assessment (LCA) to determine these environmental impacts. Also, the economy of sharing is gradually established and follows innovative uses of the car. New mobility systems emerge and compete with the classical system of sales of vehicles. These new uses of the automobile mainly take the form of car-sharing. In the future, it will become essential to evaluate these services from an environmental point of view.Some studies of the use of car-sharing already demonstrate important consequences such as reductions in the number of vehicles and in the number of kilometers traveled but also an increase in the use of other means of transport. However, to my knowledge, there is no LCA-based method to quantify the environmental benefit of the use of a car-sharing service in relation to the use of vehicles for exclusive use by the owner but also which would eco-design these services and the vehicles intended for these services.As part of this six-month project, a LCA approach was implemented to a PSA B2C (business-to-consumers) car-sharing service called “Emov” with a fleet of 500 Citroën C-Zero electric vehicles. The goal was to compare the use of Emov in Madrid, Spain with the urban use of a private Internal Combustion Engine (ICE) vehicle and a battery electric vehicle for one user characterized by its frequency, its average time and its average distance of use over a defined period. Thanks to a modeling of the service on the LCA software Gabi and by controlling over the input parameters related to the Emov service and the parameters related to the user's use of the service (variable parameters), it was therefore possible to show the influence of these parameters on the final results. Furthermore, it was possible to show also in which scenario it was more environmentally beneficial to use the service rather than a private vehicle. For the study, six impact indicators were chosen: the potentials for global warming, photochemical oxidation, air acidification, water eutrophication, resource depletion and primary energy demand.Using Emov’s big data to inform the service parameters and then varying the service user's usage parameters, it was possible to conclude that whatever the user's urban mobility needs, it is more beneficial to use the service than a private ICE vehicle for five of the six impact indicators. Only the acidification potential indicator (SO2 equivalent) is worse when using the service, which can be explained by the manufacture of the batteries of the Emov vehicles.

Thesis (M.S.)--Missouri University of Science and Technology, 2010.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 7, 2010) Includes bibliographical references (p. 44-46).

Reinforced concrete (RC) bridge decks are exposed to chlorides from deicing salts. Chloride ingress in RC initiates corrosion of the reinforcing steel. The high costs of corrosion have sparked interest in service life design of bridge decks. This thesis characterized the exposure conditions of Virginia, including temperature and surface chloride concentration, as well as Virginia concrete mix properties, including initial chloride concentration and chloride migration coefficient. The service life estimations for a case study bridge in Virginia from three service life models were compared. The first model is based on the fib Bulletin 34 Model Code for Service Life Design, the second is a finite element solution of the fib Bulletin, and the third accounts for a time-, temperature-, moisture-, and concentration-dependent apparent diffusion coefficient. A sensitivity analysis was completed on the three models showing that the most important variables in these models are the aging coefficient and surface chloride concentration. Corresponding life cycle cost analyses were completed for plain and corrosion resistant reinforcing steel. This thesis showed that the error function solution underestimates chloride ingress. The life cycle cost analysis of plain and corrosion resistant reinforcing steels show that overestimation of service life leads to underestimation of life cycle costs.
Master of Science

Vacuum insulation panels (VIPs) represent a high performance thermal insulation material solution offering an alternative to thick wall sections and large amounts of traditional insulation in modern buildings. Thermalperformance over time is one of the most important properties of VIPs to be addressed, and thus the ageing effectson the thermal properties have been explored in this work. Laboratory studies of ageing effects are conducted over a relatively limited time frame. To be able to effectivelyevaluate ageing effects on thermal conductivity, accelerated ageing experiments are necessary. As of today, nocomplete standardized methods for accelerated ageing of VIPs exist. By studying the theoretical relationshipsbetween VIP properties and external environmental exposures, various possible factors for accelerated ageing areproposed. The factors that are found theoretically to contribute most to ageing of VIPs are elevated temperature,moisture and pressure. By varying these factors it is assumed that a substantial accelerated ageing of VIPs can beachieved.Four different accelerated ageing experiments have been performed to study whether the theoretical relationshipmay be replicated in practice. To evaluate the thermal performance of VIPs, thermal conductivity measurementshave been applied.The different experiments gave a varying degree of ageing effects. Generally the changes in thermal performancewere small. Results indicated that the acceleration effect was within what could be expected from theoreticalrelationships, but any definite conclusion is difficult to draw due to the small changes. Some physical changes wereobserved on the VIPs, i.e. swelling and curving. This might be an effect of the severe conditions experienced by theVIPs during testing, and too much emphasis on these should be avoided.
Vakuumisolasjonspaneler (VIP) er en høyisolerende materialløsning som kan være et alternativ til tradisjonell bygningsisolasjon. På grunn av god isolasjonsevne kan man ved bruk av VIP redusere veggtykkelsen og fortsatt tilfredsstille energikravene som stilles til moderne bygninger. En av de viktigste egenskapene for VIP er evnen til å bevare høy termisk ytelse over tid. I den sammenheng har aldringseffekter for VIP blitt undersøkt. Siden laboratoriestudier av aldringseffekter gjøres i løpet av et relativt kort tidsrom, er akselerert aldring nødvendig for å få evaluert termiske egenskaper over tid. Det finnes pr. i dag ingen standardisert metode for akselerert aldring av VIP. Det finnes likevel flere studier av sammenheng mellom klimaforhold og VIP egenskaper. Spesielt er gass og fuktdiffusjon inn i panelet behandlet grundig i litteraturen. Basert på dette er det foreslått flere mulige faktorer for aldring av VIP. De faktorene som er funnet å bidra mest til aldring av VIP er temperatur, fuktinnhold i lufta og utvendig lufttrykk. Ved å variere disse faktorene er fire forskjellige aldringsforsøk beskrevet og gjennomført.Konduktivitetsmålinger er blitt brukt som et mål på de termiske egenskapene til de testede VIPene. De forskjellige forsøkene viste forskjellig grad av aldringseffekt. Generelt var endringen i konduktivitetsverdier liten. Resultatene indikerer at akselerasjonseffekten var innenfor hva som kan forutsies fra de teoretiske sammenhengene. Likevel er det vanskelig å trekke noen definitive konklusjoner, både siden endringen var så liten, og fordi få paneler ble brukt i forsøkene. Noen fysiske endringer ble observert under forsøkene. Blant annet este et av panelene noe ut, mens et annet bøyde seg permanent. Man burde likevel ikke legge for mye vekt på disse effektene, siden de kan skyldes de relativt ekstreme testforholdene.

This thesis presents a survey of different tools, used byenvironmental consultants in Sweden, for their recommendationsof building products and components in different constructionprojects. The goal was to identify possible improvements of thetools so that life cycle methodology could be used to a largerextent than today. This thesis also presents a general methodfor multi-criteria assessment. The purpose of this generalmethod was to show how assessment of environmental impacts,cost and prediction of service life have to be combined for acomprehensive view over all the criteria that influencedecision-making in different construction projects.

The evaluation of the present role of environmentalconsultants in the building process in Sweden and their toolsis based on a literature study together with interviews.Advantages and disadvantages of the different tools fordecision-making have been identified. It was found that thereare many improvements to be made, for example, concerningbuilding product declarations. The declarations have to containmore quantitative data and the guidelines have to be furtherdeveloped to secure equivalence in product comparisons. Thestudy showed that an environmental consultant seldom makes anelaborate assessment of aspects other than environmentalimpacts. Others, for example, the client or contractor,consider aspects of economy and technical functionality.However, there is a need of a more comprehensive view wherecosts and technical functionality are included in theassessment together with environmental concerns. If differentaspects are treated separately there is a risk ofsuboptimisations. This need has been identified by for exampleconsultants and the commission of the Swedish government and isoften emphasised by the building material industry.

In Life Cycle Assessment (LCA) the functionality, as well asthe time of use should be reflected in the definition thefunctional unit of the study. Calculations of Life Cycle Cost(LCC) also include the time aspect and compared systems shouldfulfil the same requirements of functionality. Therefore, it isof obvious interest to find a method that brings together LCA,LCC and service life planning (with estimations of servicelives). The presented method of multi-criteria assessment is toa large extent considered to be of practical use for practisingconsultants in their recommendations of the preferable choice,as soon as a pedagogical interface has been developed. Inaddition, a simplified LCA technique has to be used, where somesystemlimits and assumptions are pre-defined. A multi-criteriaassessment approach is one step ahead to fulfil therequirements of the authorities and the society. Themulti-criteria approach also helps the building sector to worktowards the goal of increased environmental concern in thesector and the overarching goal of an environmental sustainablesociety.

Key words:life cycle assessment, LCA, environmentaldeclarations, building product declarations, environmentalconsultants, tool for decision-making, service life planning,estimation of service life, the factor method, multi-criteriaassessment

The built environment usually constitutes a very important part of the real capital of a nation, and the construction sector represents more than 10% of the yearly Gross National Product of the industrialised world. Good planning of all construction is important, and consideration of the service life of the work is of great interest and is a significant aspect of sustainability considerations. The need for more knowledge about degradation of materials, for structured methodology, and for working tools for those involved in the planning process, has resulted in an extensive effort in pre-normative research and standardisation regarding this field.

This thesis presents a discussion on service life planning and the role of the Factor Method in such work, and especially, discussion of modification and development of the methodology. In the design process, the need to evaluate the service life of products is a great challenge, as the results will depend on both material properties and the environment in which the material is placed or used. A practical solution has to be based on a good knowledge in the field, but also on a sound working strategy, to ensure that different design scenarios can be compared in a standardised or structured way. The Factor Method is a promising working tool for such an evaluation and comparison, but is as such, still more of a methodology, than a method. Examples of the use of the methodology are still very limited, and the method as such, is much discussed by researchers. However, its future will depend upon how practical it will be to apply in use. The method is useful to estimate the service life of products, based on a known reference service life and a number of modifying factors. These factors in turn depend on the conditional differences between the specific project and the reference, in-use conditions. This thesis discusses the required precision of such a methodology, especially in light of inherent distributions in material properties, and the fact that the consequences of failure are often very limited. In such cases, the standardised Factor Method is considered to be quite useful, and should give the parties involved a good means for working in a structured and systematic way.

This research aims at enhancing the service life of the prestressed concrete bridge girders, using fiber-reinforced polymer (FRP) composite shell on the lower flange to impede the ingress of deleterious elements into the concrete. The FRP shell would help to retard the resulting deterioration reactions and achieve more durable bridges for a considerably increased service life. The behavior of prestressed concrete bridge girders with FRP shells on the tension flange was investigated experimentally.The flexural characteristics of FRP shell and concrete interface along with the effect of the steel reinforcement ratio were studied experimentally. This FRP shell was bonded around the lower part of the concrete beams, constructed with four different reinforcement ratios. The beam specimens with the FRP shell showed a significant enhancement in their strength, stiffness and energy absorption capacities, as compared with the associated control beams. The flexural behavior of cast-in-place prestressed concrete beams with FRP shell was studied to examine the contribution of the bonded FRP shell to the strength, stiffness, ductility and energy absorption capacity of prestressed concrete beam specimens, for five different levels of prestressing. The initial cracking, yield and ultimate strengths of the beam specimens with FRP shell were significantly higher than those of the associated control beam specimens. The FRP shell and the prestressing force enhanced the strength and stiffness of the beams. The long-term durability of the FRP shell to act as a barrier against ingress of aggressive elements, such as moisture and chlorides into the proposed FRP shell-concrete system, was examined experimentally in a preliminary manner. Detailed tests on concrete specimens reinforced externally with FRP shells subjected to accelerated moisture and salt solution at control temperatures were performed. In addition, scanning electron microscopy (SEM) was used to determine the effects caused by aging, with time, temperature and chloride injection pressure. The FRP shell, acting as a barrier, showed a significant resistance against chloride ingress by significantly slowing down the chlorides ingress rate and the total amount of chlorides. For a prestressed concrete girder with an FRP shell, the accumulated time for chloride penetration and reaching the level of prestressing steel strands was predicted to be more than 135 years. These results suggest that the FRP shell is quite effective in improving the durability characteristics of prestressed concrete girders and can significantly extend their service life.
Cette recherche vise à améliorer la durée de vie des poutres de pont en béton précontraint à l'aide de coquilles de composite de polymères renforcés de fibres (FRP) appliquées à la semelle inférieure pour empêcher l'infiltration d'éléments nocifs dans le béton. La coque en FRP permettrait de retarder les réactions de détérioration et de réaliser des ponts plus durables ayant une durée de vie considérablement accrue. Le comportement de ces poutres de a été étudié expérimentalement. Les caractéristiques en flexion de la coquille en FRP et de son interface de béton ainsi que de l'effet du pourcentage d'armature d'acier ont été étudiés expérimentalement. La coquille en FRP a été collée autour de la partie inférieure de poutres béton construites avec quatre pourcentages d'armature. Les spécimens de poutres avec la coquille de FRP ont montré une amélioration significative dans leurs résistances, rigidités et capacités d'absorption d'énergie par rapport aux poutres sans coquilles. Le comportement en flexion de poutres de béton précontraint coulées en place avec la coquille de FRP a été étudié afin d'examiner la contribution de la coquille à la résistance, rigidité, ductilité et capacité d'absorption d'énergie pour cinq pourcentages de précontraintes. La limite de fissuration, la limite d'élasticité et la limite ultime des spécimens avec FRP étaient sensiblement supérieures à ceux des spécimens sans coquille. La coquille en FRP et la force de précontrainte a amélioré la résistance et la rigidité des poutres. La contribution à la durabilité à long terme de la coquille de FRP contre les infiltrations d'éléments agressifs dans la coquille et le béton, tels que l'humidité et les chlorures, a été étudiée expérimentalement de façon préliminaire. Des tests accélérés sur des échantillons de béton renforcés extérieurement avec des coquilles de FRP ont été effectuées en les soumettant à l'humidité et une solution saline à température contrôlées. La microscopie électronique (SEM) a aussi été utilisée pour déterminer les effets du vieillissement par rapport au temps d'exposition, à la pression d'injection, à la température et aux chlorures. La coquille de FRP, agissant comme une barrière, a augmenté significativement la résistance contre la pénétration des chlorures en réduisant significativement le taux de pénétration des chlorures et de la quantité totale d'ions chlorure. Pour une poutre en béton précontraint avec une coque en FRP, le temps total pour que les ions chlorure atteignent les câbles d'acier de précontrainte est estimé à 135 ans. Ces résultats suggèrent que la coquille de FRP est très efficace pour améliorer la longévité des poutres en béton précontraints et peut allonger considérablement leur durée de vie.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2009.
Includes bibliographical references.